Formation of tool bits other than those of the simplest or symmetrical shapes presents the problem of getting a holding fixture to move a bit blank in such a geometric pattern relative to a grinding wheel that the latter will form a predetermined, complex configuration. Examples of such bit shapes are those having opposite or adjacent side and/or end faces of different curvature or configuration, including such tungsten carbide inserts mounted in rock bits, etc. One way to produce such uniform bit shapes is by use of interengaging cam and camways as shown in U.S. Pat. No. 2,491,346. However, use of such fixture does not allow variation from the set cam pattern. Some other fixtures permit a limited radial adjustability of a workpiece shaft relative to its rotary axis, such as seen in U.S. Pat. No. 3,094,821. In contrast, an easy and progressive adjustability for positioning such workpiece so as to obtain a calculated pattern selected from a wide range of possibilities would be highly desirable.